Any advantage of bigger valves in 452 heads?

[squeakfinder]

Basically, what the subject said.

My machinist is putting together a kit for my 440 build. So he's getting some prices on new stainless valves. My goal is to get at least 400 hp out of the engine. He is insisting on bigger intake and exhaust valves. Should I do it?

[jg68]

Basically, what the subject said.

My machinist is putting together a kit for my 440 build. So he's getting some prices on new stainless valves. My goal is to get at least 400 hp out of the engine. He is insisting on bigger intake and exhaust valves. Should I do it?

If you do it, have them put a 75* throat cut, then just blend it in, From taking with the experts & my own esp., putting larger valves in without any bowl work will not yeild much of anything, you have to take advantage of the larger valves to benefit from them, Or, if the seats are so bad, that you need to go larger, otherwize, just stay with the 208/174s, either way, do a 30* back-cut on them. 400 ponies is nothing with the small valves, my 451 with very mild 906s with small stainless valves made over 500 HP.

[Challenger340]

I second what jg68 said, good advice.

[dave571]

Your machinist is out to lunch.  Bigger valves are not needed for 400 hp.  No way no how.

Stock valve size can yeild 500 or better. The port work, and cam selection is WAAAAYYY more critical than valve size.

FWIW The 440 I run moves my 3800 pound car into the 11's with stock valve size.

[Challenger340]

Your machinist is out to lunch. Bigger valves are not needed for 400 hp. No way no how.

Stock valve size can yeild 500 or better. The port work, and cam selection is WAAAAYYY more critical than valve size.

FWIW The 440 I run moves my 3800 pound car into the 11's with stock valve size.
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I agree with you to Dave, it's NOT absolutely necessary to have the big valves to make 400 H.P., but it is easier to "make it" with them.

[firefighter3931]

My  ....the stock valve size is fine for that power level. As mentioned above, some porting and good component matching is more important than simply installing a larger valve in the head. 



Ron

[is_it_EVER_done?]

rotsparts: If all you want is 400 Hp, then bigger valves, and the expense that that intails is truly a waste of time and money, but to address your posted question about any advantage, yes there is, as the heads will flow better than stock valve sizes, but it forces a more important question, which is is it cost effective.

To this the answer is NO! Please tell us what your machinist plans on charging to install larger intake and exhaust valves (and hard seats to accommodate them) in your 452's, as I bet it will be close enough to the cost of a set of E-heads that the slight difference would be a total waste compared to simply switching to the E-heads.

If you don't want to go to the E-heads, simply have your machinist grind a 3 angle valve job on your heads with the final (throat) cut at 70 to 75 degrees. This will give you about 75% of the flow improvement that most porting jobs will give. Plus if you have the valves backcut. you will be hard pressed to keep it at only 400 HP.

Should your heads "need" an extensive rebuild, go with the E-heads, as even a stock type rebuild, with a current tech (stock type) cam can easily achieve around 500 HP with headers and a carb upgrade, and may even be cheaper than rebuilt (stock) heads, as they come with decent valve springs, which will probably be additional with the 452's.

[Chryco Psycho]

I do a lot of Iron heads & have the hard seats installed on the exhuast side & install the larger 1.81 valves , this adds more floor to the exhuast port & will make gains , the intake is generally left stock

[squeakfinder]

rotsparts: If all you want is 400 Hp, then bigger valves, and the expense that that intails is truly a waste of time and money, but to address your posted question about any advantage, yes there is, as the heads will flow better than stock valve sizes, but it forces a more important question, which is is it cost effective.

To this the answer is NO! Please tell us what your machinist plans on charging to install larger intake and exhaust valves (and hard seats to accommodate them) in your 452's, as I bet it will be close enough to the cost of a set of E-heads that the slight difference would be a total waste compared to simply switching to the E-heads.

If you don't want to go to the E-heads, simply have your machinist grind a 3 angle valve job on your heads with the final (throat) cut at 70 to 75 degrees. This will give you about 75% of the flow improvement that most porting jobs will give. Plus if you have the valves backcut. you will be hard pressed to keep it at only 400 HP.

Should your heads "need" an extensive rebuild, go with the E-heads, as even a stock type rebuild, with a current tech (stock type) cam can easily achieve around 500 HP with headers and a carb upgrade, and may even be cheaper than rebuilt (stock) heads, as they come with decent valve springs, which will probably be additional with the 452's.

As far as cost to do the machine work on the heads, it was $465.00 for the labour. Thats about all I could get out of him and thats pretty vague.

So I called him up and told him  I changed my mind, I picked everything up Friday and payed for what he had done (boring the block and cleaning heads)

This is supposed to be fun. But he's put me through so much stress with his BS I think it gave me cancer

Its one thing for me to do most of the work and spend $2500.00 and not be happy with the results, all I have is myself to blame. But to be brow beat into doing it someone else's way and have over $5000.00 spent on it is another.

So, I'm gonna need to drive a little farther and take my business elsewhere.

Oh but, I have learned a few things from him, like decking a block and shaving the heads won't effect compression.

Yep, the guys at work got a good laff outta that one.

[Chryco Psycho]

you need to go elsewhere

[jg68]

you need to go elsewhere

I agree, that guy needs to get off whatever he's smokin , now i did have a total of about 450-500.00 in my 906s, but that was for everything, new guides & (bosses cut down), harden seats, perf. VJ including 30* back-cut, cleaning, new seals, milled .005, new 208/174 stainless valves (10* locks), i had springs already, but that was ready to bolt on, i wen't 10.91 best with these heads, i'll bet they didn't flow over 220 int./160 ex.

Don't get too discouraged, you'll find someone who will work with you, for what your doing, a nice stock set of heads will work great, just a good perf. VJ & a 30* back-cut.

[squeakfinder]

I just got off the phone with Shaun at the Napa machine shop in The Dalles, Oregon. What a breath of fresh air that was. He listened to me and what I needed to do. He said it might be the first of next week before he could do anything (good sign, he's busy). I told him my main concern was getting cylinder's sized and honed to the piston's, he said being that the block was clean and bored he figured $60.00.

I checked with my mic. 4.377 is what I came up with on the cylinder bores. It was pretty consistent on all bores. 4.380 would be .060 over so hopefully there is enough meat left over for sizing and honing.

Told him I still need to order pistons from maybee Summit Speed pro L2335F. As far as the heads I haven't decided. I'm going to look at them a little closer and see if the valves are sinking in, and have a friend of mine help me check the guides for were. If its not to bad, I do have access to a valve grinder at work .

Otherwise, new guide and valve seat inserts I'm looking at $425.00 with Shaun plus cost of valves.

[Mike DC]

 
I'm in agreement with the general tone of the feedback so far.
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I vote to throw E-heads onto the thing and drive it. 

The flood of cheap/decent aftermarket BB wedge cylinder heads in the last couple years have made messing with old stock iron heads less practical by the month.  The base model E-heads are cheap, decent, and they're not just a bunch of huge ports to kill your low-end torque.  They're getting a lot of the their power gains from having reasonable port sizes and just being more precisely made.  (Read: much less porting work needed as they come right out of the casting mold.)

If you wanna mess with any head (be it E-heads or others), then I'd vote to get them pretty well bowl ported and maybe put in some back-cut valves.  If you're serious enough to wanna start upping valve sizes, serious porting work, etc?  Then there's probably already an aftermarket cylinder head out there to do the job better.
 

[Rayzor]

Otherwise, new guide and valve seat inserts I'm looking at $425.00 with Shaun plus cost of valves.

If you feel like going for a bit of a road trip down here to sweet home "near Eugene" The guy that does all my machine work speaks mopar. He put the hard seats intake and exhaust plus guides and milled the heads all assembled with the valves and springs I provided for 300 bucks. He is a retired old guy that builds hot rods and engines now so he is easy to deal with. He has built about 20 different engines for me so I really trust his work. PM me if you want his number.

[squeakfinder]

Wow. Thanks Rayzor. I'll give that some thought. It would be nice to deal with someone like that.